Magnetic shielding spring

Abstract

A magnetic tape cassette comprising a housing having an apertured wall to admit a magnetic head, tape guiding means, tape pressure means provided opposite to the aperture and a leaf spring adapted to press the tape pressure means against the tape when a magnetic tape is present in the cassette. The leaf spring consisting of one strip of a soft-magnetic metal alloy having an amorphous structure also serves as a magnetic shielding.

What is claimed is: 
     
       1. A magnetic tape cassette comprising a housing having circumferential walls, one of said walls having an aperture for admitting a magnetic head connected to a magnetic tape apparatus, tape guiding means for guiding a magnetic tape present in the cassette past said aperture, tape pressure means disposed opposite said aperture, a leaf spring arranged to press the tape pressure means against the tape when a magnetic tape is present in the cassette, and means for magnetically shielding a region in the cassette adjacent said pressure means, characterized in that the leaf spring and the means for magnetically shielding together consist of a unitary element which is a strip of soft magnetic metal alloy having an amorphous structure. 
     
     
       2. A magnetic tape cassette as claimed in claim 1, characterized in that said strip is at least 80% amorphous. 
     
     
       3. A magnetic tape cassette as claimed in claim 1, characterized in that said strip is at least 95% amorphous. 
     
     
       4. A magnetic tape cassette as claimed in claim 1, 2 or 3 characterized in that the metal alloy has a composition based on iron together with cobalt or nickel and contains from 10-30% by weight of vitrifying agents. 
     
     
       5. A magnetic tape cassette as claimed in claim 4, characterized in that the leaf spring is a strip of nickel iron alloy produced by electro-deposition. 
     
     
       6. A magnetic tape cassette as claimed in claim 1, 2 or 3 characterized in that the leaf spring has soft magnetic properties which do not vary under resilient movement. 
     
     
       7. A magnetic tape cassette comprising a housing having circumferential walls, one of said walls having an aperture for admitting a magnetic head connected to a magnetic tape apparatus, tape guiding means for guiding a magnetic tape present in the cassette past said aperture, and tape pressure and shielding means disposed opposite said aperture, said tape pressure and magnetic shielding means comprising a leaf spring, characterized in that the leaf spring provides the shielding function of the tape pressure and shielding means, and that the spring is a unitary element which consists of a strip of soft magnetic metal alloy having an amorphous structure and a composition defined by the formula:   (Fe.sub.x Co.sub.1-x).sub.1-y (Si.sub.1-z B.sub.z).sub.y     wherein   0.03<x<0.25; 0.1<y<0.3; 0.2<z<1.   
     
     
       8. A leaf spring for providing a biasing force and magnetic shielding, suitable for use in a magnetic tape cassette, consisting of one unitary strip of a soft magnetic metal alloy having an at least 80% amorphous structure. 
     
     
       9. A leaf spring as claimed in claim 8, characterized in that the strip has an at least 95% amorphous structure. 
     
     
       10. A leaf spring as claimed in claim 8 or 9, characterized in that the strip consists of an electroplated nickel iron alloy. 
     
     
       11. A leaf spring as claimed in claim 8 or 9, characterized in that the alloy has soft magnetic properties which do not vary under resilient movement, said alloy having a composition based on iron together with cobalt or nickel and containing from 10 to 30% by weight of vitrifying agents. 
     
     
       12. A leaf spring suitable for use as a combined spring and shield in a magnetic tape cassette, characterized in that the spring consists of one unitary strip of a soft magnetic metal alloy having an amorphous structure and a composition defined by the formula:   (Fe.sub.x Co.sub.1-x).sub.1-y (Si.sub.1-z B.sub.z).sub.y     wherein   0.03<x<0.25; 0.1<y<0.3; 0.2<z<1.